Method for manufacturing a mineral fiber product

ABSTRACT

A method for manufacturing a mineral fiber product includes centrifuging mineral fibers with a spinner, forming a veil of the mineral fibers moving in the direction of the axis of the spinner, directing toward the veil, from a position within the veil, organic material to cause intermingling of the organic material and the mineral fibers, and, collecting the intermingled organic material and mineral fibers to form a mineral fiber product.

This is a continuation application of U.S. patent application Ser. No.08/078,909, filed Jun. 21, 1993, now U.S. Pat. No. 5,458,822, issuedOct. 17, 1995.

TECHNICAL FIELD

This invention relates to the production of mineral fiber products and,in particular, mineral fiber products having an organic or polymerapplied thereto. More particularly, this invention relates to making amineral fiber product with a novel way of applying polymeric material tothe mineral fibers.

BACKGROUND OF THE INVENTION

Mineral fiber products, particularly products made of glass fibers, aretypically made as either continuous fibers or discontinuous fibers.Various organic coatings are applied to these fibers for protecting thefibers from abrasion, for connecting the mineral fibers to each other toform a structural product, and for providing compatibility of themineral fibers with other materials, such as the compatibility betweenthe reinforcement fiber and a plastic matrix. In the case of insulationproducts, the mineral fibers are bonded together by organic material,such as a phenol/formaldehyde binder, to form a spring-like matrix whichcan recover after compression during packaging.

The application of organic material to the mineral fibers can takeseveral forms. Continuous mineral fibers can be run through a bath oracross a coater to apply a coating to the fibers, such as during theapplication of a size to continuous fibers. Also, the organic materialcan be sprayed onto the mineral fibers. This method is commonly used inthe manufacture of insulation products where a cylindrical veil ofmineral fibers is met with the sprays of the phenol/formaldehyde binder.Typically, the phenol/formaldehyde binder contains urea, and has amolecular weight of around 600 in the uncured state in the aqueoussolution being applied to the glass fibers.

One of the problems with applying aqueous organic binders of the priorart to cylindrical veils of mineral fibers is that a portion of thebinder tends to evaporate prior to contact between the liquid binderdrop and a mineral fiber in the veil. The evaporated binder materialbecomes a contaminant in the exhaust air stream of the process and mustbe cleaned up in order to avoid pollution problems. Also, the bindermaterial on the mineral fibers tends to be sticky, requiring extensivecleaning of the fiber collection apparatus to prevent the build-up ofclumps of glass fiber insulation material which can drop into theproduct and cause a product defect.

Another problem associated with the application of binder to insulationproducts is that the low molecular weight phenol/formaldehyde bindermaterial does not have some of the desirable characteristics of other,higher molecular weight polymeric material, such as polyethyleneterephthalate (PET), polypropylene or polyphenylene sulfide (PPS). Aprimary problem with the low molecular weight binder material is that acuring process is required, and this usually has operating penaltiessuch as the capital and operating cost of a curing oven, the cost ofhandling pollution problems, degree of cure problems and productintegrity problems. If higher molecular weight polymers could be appliedto mineral fibers to produce insulation products, some improved featurescould be realized.

Heretofore, attempts to apply higher molecular weight binders to mineralfibers to produce an insulation product have not met with great success.One of the problems with the attempts to apply higher molecular weightpolymers, as well as the lower molecular weight phenol/formaldehydebinders to veils of glass fibers, has been that the application of thematerial is very uneven, resulting in differences in the amount of thebinder material applied to different portions of the insulation product.It would be advantageous to be able to apply these binder materials in amore uniform manner to produce a more uniformly distributed binderedproduct.

SUMMARY OF THE INVENTION

There is now been developed a method for manufacturing a mineral fiberproduct which includes the step of directing polymeric material fromwithin a cylindrical veil of mineral fibers into entanglement with themineral fibers in order to produce an improved mineral fiber product. Bydirecting the binder material from a position within the veil, thematerial is able to achieve a much more uniform intermingling with themineral fibers in order to provide a unique uniformly bindered product.The method of the invention enables the application of binder materialshaving molecular weight in excess of 1,000, preferably in excess of10,000, and most preferably in excess of 100,000.

According to this invention there is provided a method for manufacturinga mineral fiber product comprising centrifuging mineral fibers with aspinner, forming a veil of the mineral fibers moving in the direction ofthe axis of the spinner, directing toward the veil, from a positionwithin the veil, polymeric material having a molecular weight greaterthan 1,000 to cause intermingling of the polymeric material and themineral fibers, and collecting the intermingled polymeric material andmineral fibers to form a mineral fiber product. It has been found thatthe product made by the method of this invention produces an insulationproduct having a greater degree of flexibility and handleability thantypical insulation products. Further, the product produced by theinvention exhibits improved recovery over standard insulation products.

In a specific embodiment of the invention, the directing step comprisescentrifuging the polymeric material with a second spinner. The secondspinner can form polymeric fibers, which are directed toward the veil.Alternatively, the second spinner can direct the polymeric materialtoward the mineral fibers in a non-fibrous form.

In a specific embodiment of the invention, the polymeric material,whether fibers or particles, is directed into engagement with themineral fibers in a heated zone so that the polymeric materials orpolymeric fibers are in a softened condition as they intermingle withthe mineral fibers of the veil. In yet another specific embodiment ofthe invention, the polymeric material is directed toward the veil in theform of a film.

In one novel aspect of the invention, a first polymeric material iscentrifuged to form a veil of first polymer fibers, and a secondpolymeric material having a molecular weight greater than 1000 isdirected toward the veil from a position within the veil to interminglewith the first polymer fibers. The resulting product includes the firstpolymer fibers and the intermingled second polymeric material.

In the specific embodiment of the invention, the first polymericmaterial is polyphenylene sulfide (PPS) and the second polymericmaterial is PET.

DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view in elevation of apparatus for carrying outthe method of the invention as applied to the centrifical fiberizationof glass fibers.

FIG. 2 is a schematic view in elevation of an alternate embodiment of apolymer spinner used in the invention.

FIG. 3 is a schematic view in elevation of yet another embodiment of apolymer spinner used in the invention.

FIG. 4 is a schematic view in elevation of another embodiment of theinvention in which a first polymer is centrifuged from a first polymerspinner and the second polymeric material is centrifuged from within theveil of the first polymer fibers.

DESCRIPTION OF THE INVENTION

The invention will be described in terms of a glass fiber formingoperation, although it is to be understood that the invention can bepracticed using other heat softenable mineral material, such as rock,slag, and basalt.

As shown in FIG. 1, glass spinner 10 rotates on axis of rotation 12 andis driven by shaft 14. The spinner is supplied by molten stream of glass16 which is centrifuged through the walls of the spinner of form glassfibers 18. The glass fibers are maintained in a soft, attenuable stateimmediately outside the spinner by the heat from annular burner 20. Theradially-traveling glass fibers are turned down by blower 21 into acylindrically shaped veil 22 of fibers, traveling downwardly, i.e., inthe direction of the axis of the spinner. The process for creating thedownwardly moving veil of glass fibers is well known in the art.

Positioned beneath the glass spinner is a rotatable device fordistributing polymeric material into contact with the veil from aposition within the veil. The embodiment shown in FIG. 1 includes theuse of a second spinner, polymer spinner 24, for distributing polymericmaterial into contact with the veil. The polymer spinner can be mountedfor rotation in any form. As shown, it can be mounted with supports 26into direct contact with the glass spinner for rotation.

The polymer spinner is supplied with stream 28 of molten polymermaterial. As shown, this stream can be fed through the hollow portion ofthe glass spinner shaft. The molten polymer can be produced or suppliedby using extruder equipment commonly known to those in the art ofpolymeric materials, such as PET.

Depending on the viscosities, surface tension and other parameters ofthe polymeric material, and on the rotation rate and orifices of thepolymer spinner, polymer fibers 30 may be produced from the polymerspinner. The polymer fibers travel radially outwardly where they meetand intermingle with the mineral fibers.

Since the glass fibers and glass spinners operate at a temperature ofaround 1,700° F., the polymer fibers are rapidly thrust into a region ofhigh temperature, causing the polymer fibers to soften. It has beenfound that some of polymer fibers melt, forming droplets or otherparticles which attach themselves to some of the mineral fibers. Othersof the polymer fibers retain their fibrous shape, resulting in thepresence of polymer fibers in the mineral fiber pack 32. The reason thatsome of polymeric material retains its fibrous shape, while otherportions of the material form polymeric particles which attachthemselves to the mineral fibers is not known. It may be that some ofthe polymer fibers do not soften to the extent required to cause them tolose their fibrous shape and turn into a more spherical shape.Alternatively, it may be that although all polymer fibers are softened,only a portion of them come into contact with mineral fibers while in asoftened condition.

In order to make sure that the polymeric material does not experience atemperature exceeding the degradation or oxidation limit, a coolingmeans, such as water distributor 35 can be used to control thetemperature regime which is experienced by the polymer fibers orpolymeric material. The water distributor can be any suitable means forsupplying finally divided moisture into the vicinity of the travelingpolymer material. Another example of a cooling means is an air flowdevice which directs air toward the polymer particles or fibers tocontrol temperature at the point where the polymeric material meets thefibers.

After the intermingled polymeric material and mineral fibers arecollected to form a pack, optionally the pack can be passed through oven34 to reset the form of the mineral fiber pack in order to producemineral fiber product 36.

One of the advantages of the invention is that it enables theapplication of high molecular weight thermoplastic binders. Heretofore,these binders have not been able to be successfully applied from outsidethe veil because of temperature restrictions.

It is not necessary for the polymeric material to be supplied in fibrousform for entanglement with the mineral fibers. The polymeric materialcan be supplied in droplet or ribbon form such as produced by polymerspinner 24A having slit orifices 40, shown in FIG. 2.

As shown in FIG. 3, polymer spinner 24B can be adapted with slotorifices 44 to produce radially traveling film of polymeric materialwhich engages the mineral fibers to form mineral fibers with polymericmaterial attached thereto.

It should be understood that other high molecular weight polymericmaterial can be used in this invention. Examples include polycarbonatematerial, polypropylene, polystyrene, and polysulfide.

It should also be understood that various amounts of polymeric materialand mineral fiber material can be provided in the ultimate mineral fiberproduct. For example, typical building insulation has about 5% by weightof phenol/formaldehyde, and the insulation product resulting from thisinvention could have a similar weight ratio of polymeric material to theweight of the mineral fiber product. Insulation molding media productscould have polymeric material within the range of from about 10 to about30% by weight of the mineral fiber product. Other mineral fiber productscould include amounts of polymeric material exceeding 50% by weight ofthe mineral fiber product and possibly even exceeding 70 percent.

EXAMPLE

The method of the invention was employed to make a PET/glass fiberproduct. The glass fiber spinner had 50,000 orifices and was operated ata throughput of approximately 1,100 lbs. per hour. The PET material wassupplied to a polymer spinner mounted for rotation beneath the glassspinner. The polymer spinner had approximately 7,000 orifices, and athroughput of approximately 50 lbs. per hour. The PET material had amolecular weight in excess of 200,000. The spinners were maintained atdifferent temperatures to successfully process the glass and the polymermaterial, respectively.

The resulting product was a uniform blend of glass and polymer fibers,with some of the polymeric material being attached to the glass fibers,and some of the polymeric material being retained as intermingledpolymer fibers. The product from this trial was found to be moreflexible and more resistant to breaking under deflection thantraditional glass fiber wool molding media. When molded in a typicalglass fiber wool molding media apparatus, the product of the inventiongave superior results, primarily in terms of resistance to breakingunder deflection. This benefit was evident when molded both as produced,and when post-treated with a resin such as a phenol/formaldehyde. Priorto molding, the product also exhibited increased recoverycharacteristics over that of the standard phenol/formaldehyde products.Also, application of ultra-violet light to the product gave a clearindication that the PET/glass fiber product had a greater uniformity ofbinder distribution than exhibited in typical phenol/formaldehydeproducts.

The method of the invention can be used to produce a fibrous productmade from two different polymeric materials. Preferably, the twopolymeric materials are intermingled through a co-fiberizing processusing coaxial centrifuges or spinners. As shown in FIG. 4, firstpolymeric fibers 50 can be centrifuged from first polymeric spinner 52and turned downward by any suitable means, such as annular blower 54 toform veil 56 of the first polymeric fibers. Positioned within the veilis second polymer spinner 58 for distributing second polymer fibers 60into the veil. It is to be understood that any means for distributingthe second polymeric material into engagement with the veil of the firstpolymer fibers can be used. Preferably, the second polymeric material isfiberized and directed toward the veil of first polymer material aspolymer fibers. It may be advantageous to provide heat into thefiberizing process, either for the first polymer fibers or for thesecond polymer material. This can be provided by any suitable means,such as annular burner 62.

A preferred fibrous product produced by this embodiment of the inventionwould include first polymer fibers made from polyphenylene sulfide (PPS)and an intermingled amount of PET material. Most preferably, the PPSfibers would be thicker than the PET fibers for greater loft of thefibrous product. The PET fibers would provide strength to the fibrousproduct. It is to be understood that the PET material could be appliedin such a manner that some of it would melt and form PET particulatematter on the PPS fibers.

It will be evident from the foregoing that various modifications can bemade to this invention. Such, however, are considered as being withinthe scope of the invention.

INDUSTRIAL APPLICABILITY

This invention will be found useful in the production of mineral fiberproducts, such as glass fiber products, for such uses as thermalinsulation and glass fiber structural products. High performance polymerfibers such as PPS can be substituted for the mineral fibers to make anall-polymer product.

What is claimed is:
 1. The method for manufacturing a mineral fiberproduct comprising:a. centrifuging mineral fibers with a first spinner;b. forming a veil of the mineral fibers moving in the direction of theaxis of the first spinner; c. forming and directing toward the veil,from a position within and spaced from the veil, organic material in theform of fibers to cause intermingling of the organic material and themineral fibers; and, d. collecting the intermingled organic material andmineral fibers to form a mineral fiber product.
 2. The method of claim 1in which the forming and directing step comprises centrifuging theorganic material with a second spinner.
 3. The method of claim 1comprising heating at least a portion of the organic fibers so that theyare in a softened condition as they intermingle with the veil.
 4. Themethod of claim 1 in which the molecular weight of the organic materialis greater than 1,000.
 5. The method of claim 1 in which the molecularweight of the organic material is greater than 10,000.
 6. The method ofclaim 1 in which the organic material comprises at least 50 percent byweight of the mineral fiber product.
 7. The method for manufacturing amineral fiber product comprising:a. centrifuging mineral fibers with afirst spinner; b. forming a veil of the mineral fibers moving in thedirection of the axis of the first spinner; c. centrifuging organicmaterial with a second spinner positioned within the veil to formorganic fibers, and directing the organic fibers toward the veil, from aposition within and spaced from the veil, to cause intermingling of theorganic material and the mineral fibers, where at least a portion of theorganic fibers become heated so that they are in a softened condition asthey intermingle with the veil; and, d. collecting the intermingledorganic material and mineral fibers to form a mineral fiber product. 8.The method of claim 7 in which the molecular weight of the organicmaterial is greater than 1,000.
 9. The method of claim 7 in which themolecular weight of the organic material is greater than 10,000.
 10. Themethod for manufacturing a fibrous product comprising:a. centrifugingorganic fibers from a first organic material with a first spinner; b.forming a veil of the first organic fibers moving in the direction ofthe axis of the first spinner; c. directing toward the veil, from aposition within and spaced from the veil, a second organic material tocause intermingling of the second organic material and the first organicfibers; and, d. collecting the intermingled second organic material andfirst organic fibers to form a fibrous product.
 11. The method of claim10 in which the directing step comprises centrifuging the second organicmaterial with a second spinner.
 12. The method of claim 10 in which thedirecting step comprises forming second organic fibers from the secondorganic material and directing the second organic fibers toward theveil.
 13. The method of claim 12 comprising heating at least a portionof the second organic fibers so that they are in a softened condition asthey intermingle with the veil.
 14. The method of claim 10 in which thesecond organic material is directed as a film toward the veil.
 15. Themethod of claims 12, 13 or 14 in which the molecular weight of thesecond organic material is greater than about 10,000.
 16. The method ofclaim 10 in which the molecular weight of the second organic material isgreater than 100,000.
 17. The method of claim 10 in which the firstorganic material is PPS and the second organic material is PET.
 18. Themethod of claim 7 in which the organic material comprises at least 50percent by weight of the mineral fiber product.
 19. The method of claim10 in which the first organic material is a polymer material, and thedirecting step comprises centrifuging the second organic material asfibers with a second spinner.
 20. The method of claim 10 comprisingheating at least a portion of the second organic fibers so that they arein a softened condition as they intermingle with the veil.
 21. Themethod of claim 19 in which the molecular weight of the second organicmaterial is greater than about 10,000.
 22. The method for manufacturinga mineral fiber product comprising:a. centrifuging mineral fibers with afirst spinner; b. forming a veil of the mineral fibers moving in thedirection of the axis of the first spinner; c. forming and directingtoward the veil, from a position within and spaced from the veil,organic material in the form of a film to cause intermingling of theorganic material and the mineral fibers; and, d. collecting theintermingled organic material and mineral fibers to form a mineral fiberproduct.
 23. The method of claim 22 in which the forming and directingstep comprises centrifuging the organic material with a second spinner.24. The method of claim 22 comprising heating at least a portion of theorganic material so that it is in a softened condition as itintermingles with the veil.
 25. The method of claim 22 in which themolecule weight of the organic material is greater than 1,000.
 26. Themethod of claim 22 in which the organic material is a polymer material.27. The method of claim 22 in which the organic material comprises atleast 50 percent by weight of the mineral fiber product.